The only trick to successful stir-frying is to have all of your ingredients prepared and ready to go before you start cooking. Once the cooking begins, it's all action and there's no time to pause.
The beauty of stir-fries is their versatility. Use this recipe as a base and change the ingredients to suit yourself. For instance, change the lamb to chicken, pork, tofu or beef. Or, use carrot and broccoli instead of the capsicum and peas. Add any hard vegetables, such as carrot, early to allow them time to cook through and any soft, tender vegetables towards the end so that they don't overcook.
Capsicums have a naturally waxy skin that helps to protect them against oxidisation and prevents loss of vitamin C during storage. As a result, their vitamin C content remains high even several weeks after they have been harvested.